Modernize the style.

test/credentials_test.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-library credentials_test;
-
 import 'dart:async';
 import 'dart:convert';
 
 import 'package:http/http.dart' as http;
 import 'package:oauth2/oauth2.dart' as oauth2;
 import 'package:test/test.dart';
 
 import 'utils.dart';
 
 final Uri tokenEndpoint = Uri.parse('http://example.com/token');
 
-ExpectClient httpClient;
-
 void main() {
+  var httpClient;
   setUp(() => httpClient = new ExpectClient());
 
   test('is not expired if no expiration exists', () {
     var credentials = new oauth2.Credentials('access token');
     expect(credentials.isExpired, isFalse);
   });
 
   test('is not expired if the expiration is in the future', () {
     var expiration = new DateTime.now().add(new Duration(hours: 1));
     var credentials = new oauth2.Credentials(
@@ skipping 134 matching lines @@
       expect(() => fromMap({"accessToken": "foo", "scopes": 12}),
           throwsFormatException);
     });
 
     test("should throw a FormatException if expiration is not an int", () {
       expect(() => fromMap({"accessToken": "foo", "expiration": "12"}),
           throwsFormatException);
     });
   });
 }